Electric discharge tube



- April 18, 193 c. BOL 1,904,195

ELECTRIC DI SCHARGE TUBE Filed May 27, 1930 INVENTOR CORNEL! 50L ATTORN EY Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE CORNELIS BOL, OF EINDHOVEN, NETHERLANDS, ASSIGNOR T0 RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE ELECTRIC DISCHARGE TUBE Application filed May 27, 1930, Serial No. 456,025, and in the Netherlands August 10, 1929.

The invention relates to electric discharge tubes such as discharge tubes for the reception or amplification of electrical ocsillations, rectifiers, glow-discharge tubes, and the like, and it is of particular importance when it is intended to reduce the dimensions of dis- ;charge tubes.

By means of supply wires the electrodes of electric discharge tubes are in connection with the external circuits. The member serving for the airtight passage of these wires through the wall is usually referred to as the stem, and ordinarily consists of a glass body which is sealed by a flange at its outer end to the wall of the tube and which projects into the interior of the discharge tube. At its inner end this tube is pinched and closed by fusion and in the press thus produced are secured the supply wires and electrode supports.

The invention concerns electric discharge tubes which are not closed by a re-entrant glass stem as is the case in the common construction. In fact, a discharge tube according to my invention has a metal closure or feet which may be sealed to the wall of the tube, in which event it must consist of a material having a suitable coefiicient of expansion. Thus, for example, ferrochromium may be utilized for this purpose. A suitable shape for such a metal foot is that of a disc which has one or more apertures for the passage of a supply lead and the edge of which is sealed to the wall of the tube.

The metal foot of the tube may also be provided with connecting members for the attachment of the tube to a holder or for the electric connection, such as contact pins, screws, springs, etc. With this mode of construction the usual base which is cemented to the glass wall and to which the said members are secured, is consequently eliminated.

This ensures a considerable saving of room, but the construction is still more efiicient if one or more of the electrodes of the tube are directly secured to the connecting members which are insulatedly provided in the metal foot. In this case not only the base but also the supply wires leading from an electrode to the usual stem and from the latter to the connecting members on the base and, in additlon, the platinum or sheath wires sealed into the glass can be dispensed with.

It is evident that the connecting members or supply leads fixed in the foot must be in- "sulated from the metal. If desired, one of them may be in electrical connection with the metal foot. The insulating fixation may be established by coating the metal foot before the latter is sealed to the wall of the tube, with a layer of glass which fills the openings in the foot around the supply leads A particular embodiment of a discharge tube according to the invention is consequently characterized in that the metal foot is coated, either entirely or partly, with glass. The advantage of this process is not only that it is very eflicacious for insulating supply leads but also that the metal is separated thereby from the vacuum of the tube so that a careful deprivation of occluded gases can be omitted.

The invention affords a great economy of space for, due to the absence of a re-entrant base of the'usual type which occupies a large portion of the volume of the tube, the discharge tube can be made shorter, while a further saving of room is obtained if the base with which a discharge tube is usually provided is combined with the foot to form one member by providing the connecting members on the foot. Owing to the fact that this single member simply follows the course of the wall of the tube without any need of projecting or re-entrant parts, the dimensions of the tube can be reduced to a minin'ium. The

overall dimensions of the tube will only.

lrious electrode systems and through which the various supply leads of the electrodes are led out of the tube. Such a tube has in this case the form of a glass bell having sealed to it a metal bottom. If needed, the various systems may be separated from one another by means of partitions.

The invention will be explained more fully with reference to the accompanying drawin in which:

Figures l and 2 are sections of an amplifier valve comprisin four electrodes.

Figure 3 represents the construction hitherto used for such a tube.

Figure 4 represents another embodiment of my invention, which concerns atriode, and

Figure 5 is a perspective view of a tube according to the invention comprising a plurality of electrode systems.

The discharge tube represented in Figures 1 and 2 has a glass outer wall 1 inside of which are arranged the electrodes, an incandescent cathode 2, a control grid 3, and an auxiliary grid 4 which is surrounded by an anode 5. The latter is secured to a support rod 6 to which are also secured glass rods 7 and 8 which carry the other electrodes. The grids comprise a metal wire which is wound on two vertical supports which at the top and at the bottom are implanted in the glass rods 7 and 8. The incandescent filament or cathode is attached at its ends to wires secured to the glass rod 8 and at the top to a spring 9 secured to the glass rod 7. The tube 1 is closed at its bottom by a metal disc 10 which constitutes the foot of the tube. At its edge the foot which is perforated for the passage of the supply leads is sealed to the glass wall of the tube. At the top the tube is closed by a metal foot 11 to which the inner grid of the tube is electrically connected.

The metal disc 10 takes the place not only of the usual re-entrant glass stem but also of the usual base for it is provided with rigid connecting pins 13, 14, 15, and 16 which, by means of glass sleeves, insulatedly pass through and are hermetically sealed to the foot, the outer ends constituting contact pins or terminals like those of the usual base, and the inner ends being connected to and supporting the electrodes. To the pin 13 is secured the support rod 6 of the electrode system so that this pin may serve as the supply lead and sole support of the anode, which is electrically connected to the said support rod. The pin 14 is electrically connected to the outer grid 4, and the pins 15 and 16 are connected to the wires attached to the ends of the incandescent cathode. On its inner side the foot is coated with a layer of glass 12 which fills the openings between the connecting pins and the metal disc and which separates the latter from the vacuum of the tube.

The feet 10 and 11 preferably consist of ferro-chromium, which is only slightly porous, and the coefiicient of expansion of which corresponds with that of the usual glass. After being exhausted the tube is sealed off at 17.

In order to demonstrate the considerable economy of space obtained with the invention, Figure 3 shows beside the .two Figures 1 and 2 whlch represent sections of a discharge tube according to the invention, the outline of the tube as the latter would look like if it were provided with a stem and a base of ordinary type.

Figure 4 represents a triode according to the invention in which the metal foot consists of a perforated disc 20 provided with a rim 21 to whlch is sealed the glass wall of the tube. A hook-shaped notch 22 serves for the fixation of the tube by means of a bayonet-joint. The electrodes of the tube are directly secured to the connecting pins 23 which are insulatedly provided in the metal foot. The electric connection of these pins with the current supply outside the tube may be established with the aid of contact springs which are secured in a socket and which when the tube is inserted in the socket come into contact with the contact pins of the tube.

Figure 5 represents an embodiment of a multi-unit tube comprising three electrode systems. In this case a perforated metal plate or foot 25 is sealed to the edge of a glass-bell 26. Through the apertures pass in an airtight and insulating manner contact pins which are electrically connected to the cathodes, anodes, and grids of each system. The three systems 27, 28, and 29 have in common an incandescent cathode 30 whose ends are secured to pins 31 and 32 and which is kept taut by means of a spring 33, so that, if due to its heating the cathode would tend to sag it is prevented from coming into contact with the grids. The whole arrangement is secured to a holder 34 provided with a rim 35 which has guides 36. Lugs 37 on the foot of the tube somewhat resiliently engage the said guides so that a clamping connection is obtained. On the bottom of the holder there are a plurality of contact springs 38 which at the insertion of the tube into the holder come into contact with the various pins of the foot of the tube.

The electrode systems may also be arranged in the form of a triangle or a polygon owing to which it is possible to use a circular foot. In this case the fixation by fusion of the glass-bell can be efiected in a somewhat easier manner.

A compact whole is thus obtained, which lends itself excellently to the manufacture of minute receiving or amplifying installations which may be utilized, for example, in hearing instruments for the use of deaf persons and for small portable apparatus for radio reception.

I claim:

1. An electron discharge device comprising an envelope having a wall with one portion of glass and another portion of sheet metal, said portions having edges, the edge of the sheet metal portion being hermetically sealed to the edge of said glass portion, a plurality of rigld conductors hermetically sealed by vitreous insulation into said sheet metal portion side by side to project on both sides of said sheet metal portion, said conductors constituting contact pins on the outer side and electrode supports on the inner side of said sheet, an electron emitting cathode and a cooperating anode mounted in said envelope and electrically connected to the inner ends of said conductors.

2. An electron discharge device comprising an envelope having a glass portion provided with an edge, a sheet metal foot having an edge hermetically sealed to the edge of said glass portion and constituting an end wall for said envelope, cooperating electrodes comprising an electron emitting cathode and an anode in said envelope, and rigid conductors extending thru and insulated from said metal foot with their outer ends forming contact pins and their inner ends joined to said electrodes whereby said conductors constitute supports for said electrodes.

3. An electron discharge device comprising an envelope having a glass portion provided with an edge, a sheet metal foot having an edge hermetically sealed to the edge of said glass portion and constituting an end wall for said envelope, cooperating elec-' trodes comprising an electron emitting oath: ode and an anode in said envelope, rigid conductors extending thru and insulated from of said sheet and hermetically sealed said metal foot with their outer ends forming contact pins and'their inner ends joined to said electrodes, and a vitreous layer on the inner surface of said foot hermetically sealed tosaid foot and to said conductors.

'4. .An electron discharge device comprising an envelope having a wall with one portion of glass and'another portion of sheet chrome iron having a thermal co-eflicient of expansion substantially the same as glass, said portions having edges, the edge of the sheet iron portion being hermetically sealed to the edge of said glass ortion, rigid conductors extending throng and hermetically sealed by vitreous insulation into said sheet metal portion side by side to project on both sides of said sheet metal portion and constituting contact pins at their outer ends and electrode supports at their inner ends, an electron emitting cathode and a cooperating anode mounted on the inner ends of said conductors in electrical connection with and supported solely by said conductors, and a vitreous layer covering the inner surface sheet and to said conductors.

to said 5. An electron discharge tube comprising a glass envelope having an aperture, a sheet metal foot having an edge hermetically sealed to the glass at the edge of said aperture to hermetically close said aperture, anode, cathode, and grid electrodes substantially concentric with each other and adjacent said foot, and rigid conductors herwith their longitudinal axes perpendicular to said foot, and a plurality of rigid conductors extending thru and insulated from said foot with their outer ends forming contactpins and their inner ends joined to said electrodes, said conductors being the sole supports and electrical connections for said electrodes.

7. An electron discharge tube comprising a glass envelope having an aperture, a sheet metal foot having an edge hermetically sealed to the glass at the edge of said aperture to hermetically close said aperture, a cylindrical anode in said envelope, a cathode coaxial with said anode,a grid between said anode and cathode, and a plurality of rigid conductors extending thru and insulated from said foot and projecting on both sides of said foot to form contact pins outside said foot, said anode being mounted on the inner end of one of said conductors and said cathode and grid being connected to the inner ends of others of said conductors.

8. A multi-unit electron discharge tube comprising an envelope having a portion of its wall of glass and the remainder a flat sheet of metal hermetically sealed at an edge to said glass portion, a pair of rigid conductors hermetically sealed into and extending thru said sheet of metal near its end with their outer ends projecting outside said sheet and, constituting contact pins and their inner ends projecting into said envelope, a straight cathode supported by and electrically connected at its ends to the inner ends of said conductors, a plurality of anodes surrounding said cathode at different points along its length, and other rigid conductors hermetically sealed into and insulated from saidsheet of metal and extending thru said sheet with their inner ends connected to and supporting said anodes and their outer ends pro ecting outside said sheet to form contact pins.

CORNELIS BOL. 

